This invention relates to thickened single phase detergent compositions for cleaning the body which have modified pseudoplastic characteristics because they contain a combination of two polymers which make them especially suitable for dispensing from containers which impart shear to the composition during dispensing and to methods for making such compositions.
Liquid synthetic detergent compositions for use on or in conjunction with the body are typically thickened to facilitate application to the hands, face, hair, etc. Such compositions can be dispensed from squeeze bottles, pump dispensers and the like. "High shear" dispensers for liquid hand detergent compositions which are commonly found in public restrooms are exemplified in U.S. Pat. Nos. 4,018,363; 4,146,156; and 4,214,676 to Cassia; 4,149,633 to Nilson and 4,429,812 to Steiner et al. These dispensers use an elastomeric bladder coupled with a valve to dispense a measured amount of detergent to the user's hands. The detergent composition is subjected to shear as it passes through an orifice to the hands. The dispensing orifice is typically located so it points downward in the direction of the floor.
One commonly used technique for obtaining thickened detergent compositions is to add inorganic water soluble salts to detergent compositions typically containing anionic or other surfactants which increase in viscosity in the presence of such salts. While this is adequate for compositions which are poured out of bottles or squeezed out of a container which is then set upright, pump dispensers which have a downward facing orifice tend to drip or leak detergent composition after the dispenser has been actuated. This creates an unsightly condition on the area below the dispenser and can even create a safety hazard if the detergent composition drips to the floor. Another disadvantage of the use of such salts to provide viscous detergent compositions is that an osmotic gradient is created because the salts tend to absorb water which forces detergent out of the dispenser and results in undesirable post-dripping of product.
Other thickeners have been tried such as various polymers such as hydroxyalkyl celluloses such as hydroxypropyl cellulose, guar gums, polyvinyl alcohols, polycarboxy polymers and the like. For examples of such compositions, see U.S. Pat. Nos. 3,326,807 (Guest et al.); 3,485,915 (Gerstein et al.); 4,576,744 (Edwards et al.); and 4,732,692 (Zabatto et al.). The Gerstein Patent employs a combination of thickening agents composed of cellulosic polymers and neutralized carboxy polymers. These accomplish thickening of the detergent compositions without a need for inorganic salts. However, some of the high molecular weight nonionic thickeners tend to produce a thickened composition which is stringy in appearance and is somewhat slimy or unpleasant to the touch. Use of inorganic thickeners such as fumed silicas or clay gellants such as hectorite or hectorite treated with quaternized organic compounds has been suggested. However, these types of gelling agents contain particulate materials which could either clog or unduly wear the valve portions of the pump type dispensers. Another problem which arises with the use of clays or polycarboxylated polymer thickening agents is that the presence of the ionic surfactants commonly used in detergent compositions often reduces the effectiveness of the thickening agent. Not all such thickening agents are suitable for use in detergent compositions, particularly when a relatively high amount of ionic surfactant is present, e.g., more than about one percent by weight of the composition.
Furthermore, the viscosity of the composition is limited by the smallest size passage that the composition must pass through inside of the dispenser. If the viscosity is not high enough, then the composition will still continue to drip from the dispenser orifice after each use of the dispenser.
To alleviate the post-use dripping problem, certain thickeners which impart pseudoplastic properties to the detergent compositions have been employed. A polymeric thickener of the type sold by Rohm and Haas Company under the trademark ACRYSOL.TM. ICS-1 Thickener has been suggested for use in surfactant-containing compositions such as shampoos, see Rohm and Haas Company Data Sheet No. CS-505 entitled "ACRYSOL.TM. ICS-1 THICKENER FOR USE IN COSMETIC AND TOILETRY PRODUCTS", July, 1981, 12 pages. This polymer imparts pseudoplastic properties to such surfactant compositions in that in the absence of shear, the composition is relatively high in viscosity. Upon application of shear such as when the dispenser pump is actuated to force detergent composition through the dispenser orifice, the viscosity of the composition drops dramatically to permit the otherwise viscous composition to pass through the dispenser orifice to the hands. When the shearing action ceases, the composition almost immediately returns to its original high viscosity state which then eliminates post-dripping of the composition from the orifice.
Use of such polymers in pump dispensers has the disadvantage of causing the composition to splash when it is dispensed due to the above-described momentary decrease in viscosity that occurs upon dispensing. This can undesirably result in having the detergent composition splashed on the floor as well as on the user's clothes and the surrounding area.
As will be more fully described below, our invention resides in the fact that we have found that a detergent composition containing a combination of a water soluble thickening agent which imparts pseudoplastic properties to the detergent composition with a small amount of a water soluble cellulosic polymer rheology modifying agent substantially eliminates the tendency for the composition to splash upon dispensing while maintaining the viscosity of the composition at a level which substantially prevents dripping of the composition from the dispenser.
Others have suggested combinations of two or more thickening agents for use in paint compositions, cosmetics and the like. As noted above, the Gerstein '915 Patent generally teaches a combination of 0.1-5% of a neutralized carboxy polymer with 0.1-2% of hydroxypropyl cellulose as a thickening agent system for cosmetic compositions. Both of these polymers are water soluble, but it doesn't address the problem we have solved. Gerstein is directed at problems involving the use of neutralized carboxy polymers in topically applied compositions where such polymers are said to "ball up and form crumbs or pills on the skin". Inclusion of the hydroxypropyl cellulose thickener is said to alleviate this problem.
The Rohm and Haas CS-505 data sheet noted above suggests the use of ACRYSOL ICS-1 Thickener in conjunction with bentonite clay to produce a free-standing gel. This concept is further described in U.S. Pat. No. 4,351,754 to Dupre which teaches that such products are useful as air freshening gels because self-supporting, firm, high strength gels are formed although lower viscosity thickened compositions can also be formed. Our compositions do not require bentonite clays and thus avoid any problems which the presence of such solid materials might introduce to dispenser pumps.
U.S. Pat. No. 4,384,096 to Sonnabend describes liquid emulsion polymers which are believed to be similar to the ACRYSOL ICS-1 thickener and teaches their use as thickeners for aqueous coating compositions such as latex paint, for cosmetics and for drilling mud compositions. Mixtures of two or more thickeners are said to be useful in column 9, lines 31-32. It does not specifically suggest our invention.
U.S. Pat. No. 4,138,381 to Chang et al. teaches another polymeric thickener employing certain polyalkoxylated groups in the polymer chain for use in thickening coating compositions. Some of the Examples employ a combination of two thickeners: the polymeric thickener described in the '381 Patent and a "gelling agent" by the name of "Colloids 581-B". The exact nature of the latter is not described in the '381 Patent. McCutcheon's Functional Materials, North American Edition, 1986, page 94 describes the composition of "Colloid 581B" from Colloid, Inc. as being a "proprietary liquid" which is emulsifiable. U.S. Pat. No. 3,973,067 describes COLLOID 581B as a defoaming agent where "COLLOID" is described as a "Colloids, Inc. trademark for a dispersion of metallic soaps in emulsifiers".
U.S. Pat. No. 4,594,108 to Greminger et al. teaches highly pseudoplastic polymer solutions which comprise a water-soluble high molecular weight organic polymer which can be a cellulosic polymer or copolymers of acrylic acid and the like and a water-insoluble, but water-swellable and water dispersible polymer such as a cellulose ether like methylcellulose having relatively low amounts of methoxy substitution (i.e., less than about 18% methoxyl content). The latter polymer must be water-swellable, but not water soluble. In the '108 Patent, it is preferred that the water soluble polymeric thickener is combined with a major amount of the second water-swellable, but water-insoluble, polymer so that the combination of the two results in a more highly pseudoplastic composition than is produced by either of the polymers alone.
Our invention employs a small amount of certain cellulosic polymers as rheology modifiers to reduce the pseudoplastic effect of the thickening polymer we use to provide pseudoplastic effects to the detergent composition. The amount of rheology modifier is less than that which is typically employed to thicken the composition. Both polymers employed in our compositions are water soluble. Thus, our invention differs from that of the '108 Patent.
Dow Corning Corporation Data Sheet No. 22-956-83 entitled "Information about Cosmetic Ingredients: DOW CORNING.RTM. Q2-7224 Conditioning Agent", 4 pages, 1983 has a Formulation I: E2-7298 Conditioner which employs 0.474 weight percent ACRYSOL ICS-1 and 0.95 weight percent METHOCEL.RTM. E4M in a silicone-containing hair conditioning formulation. In this formulation, a hydroxypropyl methylcellulose is employed and its amount is far in excess of the amounts of cellulosic polymer employed in our compositions.